1. Field of the Invention
The present invention relates to an electrical connection box for automotive vehicles and particularly to those electrical connection boxes which are designed to form internal circuits by wires and cramping terminals for connecting a multitude of external electrical circuits including e.g. fuses and relays in such a compact manner as to rationally realize joint connections of a wiring harness. Especially, the present invention is designed to reduce the number of kinds of parts of those electrical connection boxes.
2. Description of the Prior Art
Prior art electrical connection boxes for easily responding to a design change of the internal circuits, have used wires (instead of a busbar that is formed by punching a conductive metal plate) so that connections between the wires and external circuits are established by the use of cramping terminals.
In the above electrical connection box, the terminals cramped with the wires are connected with external circuits such as connectors, relays, fuses, etc. to be fitted in their receptacles formed projectingly on the outer wall of an upper casing and/or a lower casing as follows. The cramping terminals are mounted so that their input/output terminal portions formed at one end project into the receptacles for the external circuits from terminal holes formed in the outer wall of the casing. Upon fitting the external circuits in their receptacles, they are connected with the cramping terminals.
In the case where the above electrical connection box is made smaller by arranging the internal circuits in a highly compact manner, the wires need to be arranged at multiple stages.
More specifically, insulating plates are disposed in the space defined by upper and lower casings, thereby forming multiple vertical stages, and the wires are arranged at these stages.
The upper and the lower casings are generally formed to have flat walls on the outer surfaces of which the receptacles for the external circuits are formed, establishing engaging surfaces for the external circuits on the same horizontal plane and formed with the terminal holes for the cramping terminals.
Therefore, if the wires are arranged at multiple stages as described above, the wire at one stage is not as distant from the respective receptacle as the wire at another stage.
For example, as shown in FIG. 7, cramping terminals 3 are cramped with an upper wire W1 arranged in the interior of a casing consisting of an upper casing 1 and a lower casing 2. Input/output terminal portions 3a of cramping terminals 3 project into a connector receptacle 4, so that the cramping terminals 3 are directly fitted and connected with mating terminals (not shown) mounted in a connector 5 to be accommodated in the connector receptacle 4. On the other hand, shorter cramping terminals 6 cramped with the same wire W1 are mounted so that their input/output terminal portions 6a project less into a connector receptacle 7 which is longer than the receptacle 4, thereby allowing the cramping terminals 6 to be fitted and connected with mating terminals mounted in a connector (not shown) to be accommodated in the connector receptacle 7.
In other words, the cramping terminals 3 connected with the connector 5 to be accommodated with the connector receptacle 4 need to project from an engaging surface 4a of the connector receptacle 4 by a distance A. On the other hand, the cramping terminals 6 connected with the connector to be accommodated in the connector receptacle 7 need to project from an engaging surface 7a by a distance B. The relationship of the distances A and B is B&lt;A.
In the example shown in FIG. 7, the cramping terminals 3 project from the engaging surface 4a by the distance A. If the cramping terminals having the same shape as the cramping terminals 3 are used in place of the cramping terminals 6, these cramping terminals also would project from the engaging surface 7a by the distance A, which is longer than the predetermined projecting distance B for the cramping terminals in connector receptacle 7.
Thus, it is necessary to use cramping terminals 6 having a shape different from that of the cramping terminals 3 so as to change the projecting distance of the input/output terminal portions from the position cramped with the wire W and, accordingly from the engaging surface.
In other words, cramping terminals of different shapes need to be prepared in conformity with the types of the external circuits to be connected, thereby causing an increase in the number of the types of the necessary cramping terminals. This leads to an increased production cost and a tedious parts management.
As also shown in FIG. 7, a distance L1 between the first wire W1 arranged on the upper surface of an insulating plate P and an engaging surface 4a of the connector receptacle 4 formed on the upper casing 1 is different from a distance L2 between a second wire W2 arranged on the lower surface of the insulating plate P and an engaging surface 4a' of a connector receptacle 4'. Specifically, L2&gt;L1.
As a result, cramping terminals 3' to be cramped with the second wire W2 need to be longer than the cramping terminals 3 to be cramped with the first wire W1. More specifically, a portion (or length) of the cramping terminal 3' between a wire cramping portion 3b' and an input/output terminal portion 3a' thereof is longer than the corresponding portion (length) of the cramping terminal 3.
As is clear from the above, an attempt to make the internal circuits more compact by arranging the wires at multiple stages results in an increase in the number of types of cramping terminals. This disadvantageously leads to increased production costs and a more tedious parts management.
In view of the above problem, it is an object of the invention to reduce the number of types of parts of such connection boxes, and particularly to enable the use of cramping terminals of the same shape even in the case where wires are arranged at multiple stages and regardless of the types of external circuits to be connected with the cramping terminals.